1. Field of the Invention
This invention relates to a method and apparatus for generating the trajectory of a saddle-shaped curve resulting from the intersection of two cylindrical conduits. In one aspect, this invention relates to an automated apparatus for generating the trajectory of a saddle-shaped curve resulting from the intersection of two cylindrical conduits.
2. Description of Related Art
Automated pipe cutters, welders, adhesive dispensers and other automated apparatuses which follow a saddle-shaped curve resulting from the intersection of two cylindrical conduits, such as tubes and pipes, are either mounted onto the cylindrical conduit, in which case the apparatus rotates about the conduit, or have a conduit inserted, in which case the conduit is rotated. For those apparatuses having a 2-axis motion controller, the parameters that determine the shape or trajectory of the end effector, e.g. tool tip, cutting torch nozzle, adhesive dispenser nozzle, are sizes of the target pipe and the intersecting pipe, angle of intersection, and offset.
Current methods for measuring pipe diameters include calipers, pi tapes, linear CCD (charge-coupled device) arrays, and other time tested devices with varying degrees of accuracy. Manually entering the pipe diameter values into a motion controller or selecting from a complete list of existing motion control programs is both time consuming and provides opportunities for errors.
Current methods for following the saddle-shaped curve resulting from the intersection of two cylindrical conduits most commonly employ mechanical cams. The end effector is attached to a mechanism that physically rides on and follows the cam. However, a different and unique cam is required for each combination of target and intersecting conduit size and purchasing a collection of metal cams to accommodate all the possible combinations of conduits is cost prohibitive for many companies.
Other methods involve modeling the intersecting conduits in a 3D CAD (computer assisted design) program, then transferring the model to CAM (computer assisted manufacturing) software which generates code used by CNC (computer numerical control) machines to follow the trajectory. However, a complete CAD/CAM/CNC system is too complex to own and they operate if one only wishes to process the saddle-shaped curve unique to intersecting cylindrical conduits.
Accordingly, there is a need for a method and apparatus for generating saddle-shaped trajectories resulting from the intersection of two cylindrical conduits which avoids the complexities of a CAD/CAM/CNC system, which does not require the use of mechanical cams, and which reduces the amount of time and opportunities for errors associated with manual methods.